Generally, a known seat apparatus for a vehicle includes a seat slide function for adjusting a position of a vehicle seat in a front/rear direction and a seat reclining function for adjusting a tilt angle of a seatback. Some of such known seat apparatuses include a so-called walk-in function, in which an operation of moving the vehicle seat in the front direction and an operation of tilting the seatback forward are performed in association with each other so that an ease of ingress to and egress from a rear seat which is provided at a rear side relative to the vehicle seat is enhanced (for example, refer to JP5104853B, which will be hereinafter referred to as Patent reference 1).
In addition, some of such known seat apparatuses include a seat lift function (or a seat tilt function) for adjusting a position of the vehicle seat in an up/down direction. As a result, degrees of freedom of the positional adjustment of the vehicle seat are even more enhanced (for example, refer to JP2012-158301A, which will be hereinafter referred to as Patent reference 2).
However, with the enhancement of the degrees of freedom of the positional adjustment of the vehicle seat, a possibility of interference between an upper end part of a vehicle seat 61 (an upper end portion of a head rest 64) and a roof 65 of the vehicle with each other also increases at the above-described walk-in operation as illustrated in FIG. 6. That is, a front portion of the roof 65 of the vehicle is positioned lower than a central portion of the roof 65 in many cases. Accordingly, depending on a position at which the vehicle seat 61 is adjusted, an amount of moving the vehicle seat 61 forward and an amount of tilting a seatback 63 forward, both of which constitute the walk-in operation, may not be assured sufficiently because of the interference between the upper end part of the vehicle seat and the roof. Therefore, there remains room for improvement in this aspect.
A need thus exists for a seat apparatus for a vehicle, which is not susceptible to the drawback mentioned above.